The present invention relates generally to heavy load transport vehicles and more particularly to a heavy load transport vehicle having a hydraulic-powered retractable upper deck.
Transport vehicles known in the art for transporting automobiles and other heavy loads generally comprise a lower deck and an upper deck which is held above the lower deck by means of fixed posts. In the past, such vehicles required use of a suitable ramp in order to mount loads onto the upper deck. Loading the upper deck became easier with the development of transport vehicles having an upper deck capable of being raised and lowered by hand operated or power operated devices. In many of these types of vehicles, the upper deck is vertically movable along support posts extending from opposite sides of the lower deck. These support posts limit the width of the load which may be carried when the upper deck is in the lowered position. Also, for those transport vehicles, where the load to be carried on the upper deck is mounted on the upper deck while the deck is in the lowered position, the support posts may restrict the width of the load capable of being carried on the upper deck. Furthermore, the support posts may make it difficult, if not impossible, to load the decks from either side of the vehicle.
The ability to carry wider loads is significant. Transport vehicles that provide only for the hauling of automobiles, for example, may at times be economically prohibitive. In the case of a transporter who delivers a load of cars to a designated location, the inability to load anything other than cars onto the transport vehicle may require the transporter to make the return trip with no load to be hauled.
The transport vehicles known in the art which have a vertically movable upper deck may be unsafe when heavy loads are mounted upon the raised upper deck. This is because at the high speeds typically reached while driving on the highway, the upper deck may be subject to lateral movement and shaking. This could compromise the vehicle driver""s ability to safely maneuver the vehicle. Furthermore, this instability could potentially lead to damage to the load being hauled or damage to the vehicle over time.
Also, a number of transport vehicles known in the art have two vertically spaced decks with a hydraulically-powered means for raising and lowering the upper deck. These vehicles often encounter problems in the operation of the plurality of hydraulic lifts which raise and lower the upper deck. In particular, these vehicles commonly have problems raising and lowering the upper deck uniformly, with all of the hydraulic lifts raising and lowering in a synchronized manner. This problem could lead to maintenance problems as well as pose a safety hazard as a heavy load carried on the upper deck could potentially fall off the vehicle if the upper deck is raised or lowered unevenly. More importantly, such a system that lacks the means to synchronize the raising and lowering of the hydraulic cylinders would require a powerful and costly driving means for actuating the hydraulic cylinders.
Trailers generally known in the art are also limited by height restrictions imposed by federal and state Department of Transportation regulations relating to vehicle height. In the fully retracted position, with the upper deck in the lowered position, the transport vehicle may carry a load upon the upper deck. However, the total height of the load must be sufficiently low to allow travel under bridges and overpasses and to otherwise comply with federal and state regulations. The design limitations of the trailers generally known in the art do not allow the upper deck to be positioned low enough to comply with statutory height restrictions while carrying such loads.
The main object of the present invention is to overcome the above disadvantages of the transport vehicles known in the art. According to the present invention there is provided a load transporting vehicle comprising a lower deck having a set of wheels near the rear portion of said vehicle and a means for supporting the front portion of the lower deck located at the front end of the lower deck; an upper deck; and a means by which the upper deck is supported above the lower deck and by which the upper deck is adjusted between a raised, unretracted position and a lowered, fully retracted position, comprising a plurality of single-action hydraulic cylinders which are each pivotably connected at one end to the lower deck via a hydraulic cylinder lower mounting pin and pivotably connected at the other end to a lift arm via an upper hydraulic cylinder bracket, a plurality of lift-arms which are each pivotably connected at one end to the lower deck and pivotably connected at their other end to the hydraulic cylinder, a stabilizer track system that is mounted to the lower deck and guides the upper deck in a vertical up and down motion and prevents the upper deck from moving in a direction transversely of the vehicle longitudinal axis.
The present invention achieves the objective of allowing wide loads to be carried upon the upper deck when the upper deck is in the fully retracted, lowered position, by virtue of its elimination of the need for support posts to raise and lower the upper deck. The present invention""s upper deck stabilizer system and the design of its lifting mechanism eliminate the need for support posts, thereby allowing wider loads to be hauled upon the upper deck while it is in the lowered position.
The present invention also achieves the objective of raising and lowering the upper deck with the lift arms being actuated in a synchronized manner. This is accomplished by virtue of a truss assembly, comprising a plurality of braces that run perpendicular to the direction of travel of the vehicle and connect each pair of lift arms at the point where the lift arms are connected to the upper deck, and a series of trusses that extend across the vehicle diagonally and connect the cross braces.
The objective of transporting loads, such as conversion vehicles, on the fully retracted upper deck is achieved by virtue of the present invention""s design which provides for the height of the fully retracted upper deck to be 42xe2x80x3 above the surface upon which the vehicle travels.